How to Avoid and Remedy Excessive Tannin Staining on Your Home’s Exterior Cedar Siding
Cedar siding is an excellent choice for a home’s exterior. Cedar is beautiful, durable, and naturally resists decay. When properly maintained, cedar siding can last for decades. A common problem that homeowners have with cedar siding, however, is extractive bleeding or tannin staining.
Many species of wood contain tannins, including cedar and redwood. These water soluble extractives have a tendency to migrate or bleed to the surface of the wood, causing discoloration to the coating. This natural phenomenon is not caused by the coating itself.
There are several precautions which need to be taken in order to minimize extractive bleeding, but it will usually occur to some extent in about the first year after the wood has been painted.
Causes of Cedar Bleeding
The primary cause for tannins to bleed to the substrate’s exterior is moisture. There are actually several reasons for cedar paneling to become badly stained due to tannins:
• The cedar needs to be properly cured. If the wood does not have a moisture content of 15% or lower before it is treated, problems will arise with excessive staining.
• The surface of the cedar must be adequately primed and sealed; this includes all edges and cut ends.
• The primer used must be tannin-stain-resistant.
• If either the flashing or water infiltration prevention is inadequate, excess moisture could get behind the siding and cause a greater amount of staining.
• If a bluish-black stain appears where the nails are, what has happened is that the wrong nail type has been used. For cedar siding, it’s essential to use nails that are either stainless steel or hot dipped galvanized.
Solutions for Extractive Bleeding
The good news is that there are ways to remove or hide the staining and prevent the problem from continuing. Some or all of the following steps may apply:
• Determine whether there are any issues creating excess moisture and correct them.
• Use a scraper or wire brush to remove all loose paint.
• Use oxalic acid or oxalic-based solution to remove the stains.
• Rinse the wood with a pressure washer.
• Give the surface at least 48 hours to dry thoroughly. Weather conditions determine how long the drying time takes.
• Using a top-quality wood primer that’s designed specifically for stain-blocking, prime the wood. You can either spot prime or apply full coverage. Apply primer to the edges and ends. The shingles should have been primed on the back before being installed.
• If there is severe staining, it’s best to apply a second coat of primer.
• Allow the primer to dry before applying high-quality paint.
• The paint you use should not be water-based latex stain or paint, since these products use water as carriers. These types of paint can create problems with extractive discoloration.
• If you are dealing with nail staining, the best course of action may be to replace the nails, to avoid further staining of the wood. But another strategy is to countersink each of the nails and swab the holes with top-quality water repellant. Then allow the repellant to dry and fill each hole with exterior wood filler.
The methods for avoiding and removing tannin staining can get complicated and confusing if you are not experienced in this type of work. To make sure the staining is done correctly the first time or to fix existing problems, allow our professional home maintenance staff to help you with any cedar bleeding and tanning staining issues that you may have.
Franklin Painting LLC – Call us Toll Free at 877-646-7774
or at our main office number 860-678-7701
2 Eastview Drive, Farmington, CT 06032